In axial flow rotary machines, rotor assemblies are driven at high rotational speeds about an axis of rotation. The rotor assemblies include rotor disks and rotor blades. Foreign objects, such as birds, hailstones or other objects, which on occasion are ingested into the engine, may strike the blades causing parts of the rotor assembly to fragment or to separate from the rotor disk. During such a failure pieces of the rotor assembly may be hurled outwardly from the rotor assembly with velocities of several hundred feet per second. Such velocities typically have components in the axial, tangential and radial directions. One device for containing such fragments is shown in British Patent Specification 1,245,415 issued to Mottram et al entitled "Improvements in or Relating to Fluid Flow Machines". Mottram shows a containment structure formed of two similar metal strip members wound together to form a helical shield about a casing. U.S. Pat. No. 2,999,667 entitled "Protective Arrangement for Use with Apparatus or Machines Having Rotating Parts" issued to Morley shows a containment structure formed of a web of interwoven wires which are continuous from one end of the web to the other. The web is disposed in coil form in a casing about an array of rotor blades.
Several patents show containment structures formed from synthetic fibers which are woven into a fabric or webbing. U.S. Pat. No. 4,057,359 entitled "Ballistic Nylon Fabric Turbine Governor Housing Shielding Means" issued to Grooman shows a flexible housing cover formed by stitching together two sections of a ballistic nylon fabric. Grooman mentions nylon, an aliphatic polyamide fiber, and Kevlar 49, an aromatic polyamide fiber available from the DuPont Corporation, as Fibers which are suitable for forming the fabric. U.S. Pat. No. 3,602,602 issued to Motta entitled "Burst Containment Means" shows a containment means formed of a winding of tape over a machinery housing and aligned with the expected path of travel of part fragments to contain the part fragments during a failure of the rotary machine. No means are provided for bonding or fastening the adjacent turns of the winding to each other or to the housing about which the tape is wound. The winding of tape is formed of a ballistic nylon material rather than of an aromatic polyamide fiber fabric such as a Kevlar fabric. Use of a Kevlar fabric restrained in the fore and aft direction along the edges outwardly of Kevlar felt trapped radially between the Kevlar fabric and a honeycomb backed steel shell is a contemporaneous recommendation for a containment structure made in a NASA Final Report entitled "Development of Advanced Lightweight Containment Systems". This report was made under NASA Contract No. NAS3-21823.
In spite of this progress in containment structures, scientists and engineers are seeking to develop containment means which are light in weight and yet which provide containment of particles such that the particles do not escape from the nacelle surrounding the engine even though the particles have substantial axial, tangential and radial velocities.